The council chief executive responsible for implementing the Conservatives' radical "easyCouncil" vision of privatised local authority services has quit to lead a Labour-led borough.

Nick Walkley, boss of the London borough of Barnet, announced his resignation on Thursday night, plunging into doubt the leadership of the Conservative-controlled council's programme of selling off services including cemeteries, transport, planning and environmental health.

Contracts worth an estimated £1bn are in the process of being let to the private sector and decisions were due to be made in the coming months, with British Telecom, Capita and EC Harris among the companies in the running to take over. Walkley was also understood to be in the process of re-organising the council management structure to remove layers that would become redundant.

Walkley launched the plan to privatise huge swaths of council services in 2009, telling the Guardian he wanted to emulate the business practices of the no-frills budget airlines easyJet and Ryanair in an attempt to create what his spokesman dubbed an "easyCouncil".

He predicted: "The kind of changes that we are currently talking about in Barnet will come thick and fast across the public sector in the next few years."

On Thursday night he sent an email to staff announcing his resignation in order to lead Haringey, which does not have any Conservative councillors. It read: "I am writing to let you all know that earlier today I was offered the role of chief executive with Haringey council and that I have accepted the post. This is obviously a hugely challenging role and one I felt unable to turn down.

"There is still a formal appointment process to be completed but I feel it is important that I inform you all personally. I will send out details of transition arrangements, which are likely to take some months, as soon as I am able."

The public service union Unison said it was astonished that Walkley had quit now given the upheaval facing services in the north London borough. "He is the architect of a commissioning model that councils no longer do anything but are left with a smaller commissioning rump," said John Burgess, the local Unison representative.

"Does he know One Barnet is not going to be a success and he thought better to jump now because it is going to get messy?"

Walkley declined to comment on his motive for leaving, save to insist it was "a personal career decision". He added: "I run a council driven by members," and said he was taking a pay cut to take on the job at Haringey. He stressed that although the contracts had not been let, the council was concluding negotiations.

"We are not in the marketplace trying to find partners," he said.

Richard Cornelius, leader of Barnet council, said: "Nick has been an exceptional chief executive who has a can-do attitude that has served Barnet well and leaves us in a good place to face the future."